WHEN I WAS invited to interview Mexican composer, arranger and performer Miguel Martínez, I was giddy with anticipation. Martínez's notoriety as one of the chief architects of mariachi music as we now know it kicked into high gear with his original solo trumpet work with Mariachi Vargas de Tecalitlán at the dawn of the 1940s. Before Martínez, most mariachis played a simple, predictable folk music, primarily showcasing only string instruments such as harp, guitar, guitarrón, vihuela (a small, high-pitched guitar) and violin. Martínez's exquisite horn blowing changed all that.

Martínez's tenure with Mariachi Vargas de Tecalitlán, the premier mariachi of that era and the reigning mariachi today, cracked the old mold. In the early 1950s, joining fellow trumpeter Jesús Córdoba in Mariachi México de Pepe Villa, Martínez put all his new notions about the music together. The result was the two-trumpet style that remains the standard in mariachi music today.

The 1940s initiated the Golden Age of mariachi music, when phonograph, cinema and radio helped launch the regional music of Jalisco to international fame. For the next two decades, immortal stars of traditional Mexican ranchera music emerged, including Jorge Negrete and Pedro Infante. As heard in more than 120 Mexican films--many now considered classics--Martínez's improvised solo trumpet counterpoint became a trademark sound behind the voices of Negrete, Infante and dozens of other stars, affirming his standing as the leader of innovative sounds.

At 75, Martínez is still considered one of the giants of Mexican music. He continues to practice his trumpet daily and recently finished composing a huapango--a folk song type from the Huastecan region of Mexico--dedicated to the city of San José, which will be performed at this weekend's fifth annual San José International Mariachi Festival and Conference.

"I wanted to dedicate a song to San Jose for all the attention and hospitality the people have given me," he says in Spanish with a winning smile. Although his home base is in Tlanepantla, on the outskirts of Mexico City, Martínez is currently an artist in residence at Villa Montalvo, and he is working on new compositions and teaching special classes at San Jose State University, including this weekend's workshops.

I meet with Martínez at the St. Claire Hotel in downtown San Jose. He is proudly wearing his traje de charro, the traditional Mexican horseman's costume adopted by the mariachi. We start by talking about the ceaseless effort that goes into the creative process. "When I'm not performing, I'm practicing, writing," Martínez says, explaining his intense work ethic. "I'm compulsive. And when I'm resting, I think about composing."

MARTÍNEZ FIRST became fascinated with music when he was 12 years old. At that time, in the 1930s, there were very few mariachis in Mexico City. There was, however, one group in his neighborhood that would stroll from cantina to cantina performing for any patron who would pay. "I would stand outside the door and listen, because they wouldn't let me in," he recalls. "When they noticed my interest, they told me to learn the trumpet because it was a novelty in the mariachi."

Unfortunately, that novelty act didn't fare well in the beginning. In many cases, the mariachis that Martínez played with had trouble getting hired because they had a trumpet player. And if they did get a gig, it was often because every other mariachi in town was booked, and then Martínez would frequently be asked not to play.

"It was an experiment in a period that was uncertain," he says. "It [the evolution] could have just as easily gone the other way." Fortunately, it didn't, and Martínez's trumpet playing sparked a new generation of sound that defines mariachi music today: a pair of horns lending its staccato lines to a melodic weave of strings, guitar, vihuela and voices.

During the remainder of the 1950s and '60s, Martínez's trumpet continued to back virtually all the ranchera music superstars, including Miguel Aceves Mejía, Lola Beltrán, Amalia Mendoza and José Alfredo Jiménez. His playing has been featured on hundreds of recordings that are now considered classics of the genre. A prolific composer as well, Martínez has created many of the instrumental works that have become mariachi standards: "La Chuparrosa," "Café Colón," "Rosas de Mayo," "Teatro Principal."

Now, Martínez says, he is looking ahead to the next generation for someone to add a new rung to the ladder of mariachi's evolution, but he has yet to find such a person.

Some argue that mariachis such as Mariachi Sol de México de José Hernández are part of that next generation, but Jonathan Clark, an instructor/historian of mariachiat San Jose State University, is not convinced.

"Relatively few mariachi recordings are being made today, and most of those can be classified as 'cover' versions of old standards, simple permutations of traditional formulas, or fusions based on inspiration from other genres," he says. "None of the aforementioned is true innovation."

Indeed, the mariachi scene in the United States presently has more vitality than in Mexico. There is only one yearly event in Mexico comparable to the mariachi festivals and workshops held in California, Arizona, New Mexico, Texas and Colorado, and it was only three years back that the "Encuentro Internacional del Mariachi" was founded in Guadalajara.

Martínez criticizes the Mexican government and media for not promoting its music. "In the media, mariachi music is dying, along with the old-timers. It's the end of an era," he says sadly, although he stresses that the music thrives independently of the media. Mariachi will continue to fill a social function--festivals, baptisms, weddings and quinceaños, the traditional 15th-birthday celebration for girls--but whether it will continue to grow creatively remains to be seen.

"The bulk of what people ask for are old songs from the golden era," Clark says. "It's amazing how many incarnations there are of these old songs. They are the bread and butter, the meat and potatoes, of mariachi music today. Even pop singers are doing contemporary versions of mariachi standards."

ALTHOUGH THE 1940s and '50s may have been the golden age of mariachi and the period in which many songs became standards, Martínez cites the '50s and '60s--the heyday of Mariachi Vargas de Tecalitlán--as his favorite era. At that time, Mariachi Vargas was traveling worldwide, says Martínez, who remembers performing for Winston Churchill, Aly Khan and Luis Mariano, among others. He even performed at the White House for President Eisenhower.

During 1964, Mariachi Vargas also traveled to Japan to entertain, along with dozens of other performing arts groups, for the 1964 Olympics. At one specific event, each group was only allowed to perform three songs, Martínez recalls. "But we kept getting ovations, and people wouldn't let us off the stage."

Finally, after their ninth song, the emcee invited anyone from the audience to come up and sing along with them. At first, no one responded. Then a young Japanese woman in a kimono stepped forward. "She didn't speak Spanish," Martínez says, "but she knew the name of the song that she wanted us to play. It was amazing. She sang it perfectly--like she had rehearsed it with us. The next day, the Japanese papers said that it was a trick. That she really was from Mexico and had practiced with us. I even remember her first name: Kideko."

Martínez has no idea what ever happened to that young woman, but he's not surprised that another young Japanese woman has found her way into the mariachi world, and will be performing at this weekend's mariachi concerts along with Mariachi Cobre and Mariachi Las Perlitas Tapatías, an all-female ensemble from Guadalajara.

A novelty in the mariachi world, Japanese singer Junko Seki first discovered mariachi music in February of '93 while visiting EPCOT Center in Orlando, Fla., where she heard Mariachi Cobre perform. Captivated by the music, she bought one of their cassettes and returned to her home in Chiba, Japan. After memorizing all of the songs, she returned to EPCOT Center to work at the Japanese Pavilion but spent all her free time at the Mexican Pavilion watching Mariachi Cobre's show.

"I bought the tape and practiced every day. The music was new to me and I fell in love with it," says Seki, who is fluent in English, Japanese and Spanish. "The harmony was beautiful. It was so emotional."

Intrigued by the young Japanese woman who consistently sang along with them in the front row, Randy Carrillo, director of Mariachi Cobre, invited Seki backstage to perform with some of Cobre's members. "I had memorized all the songs and couldn't help it. I was singing so loud that they heard me. My gosh. That was so great to me. They let me sing with them. I was so happy," says a teary-eyed Seki after apologizing for being so emotional. "I became a groupie."

Although her friends think she is crazy, the 25-year-old is set on becoming a professional mariachi. "It gave something to me, to my heart," she explains.

For the past two years, Seki has performed with Mariachi Cobre at the Tucson International Mariachi Festival, where she has impressed audiences with her melodic voice and knowledge of the music. This will be her first time performing at the San José International Mariachi Festival and Conference.

Along with concerts and a Mass and procession (Sunday, 10am, at the San Jose Civic Auditorium) mariachi workshops will be featured at the festival. Tickets are sold out for Saturday's concert, but some are still available for Friday, and, of course, Sunday's mariachi festival is free and open to the public. Local and regional mariachi groups will be featured, along with more than 75 booths with crafts, food and beverages. Proceeds from the festival help underwrite operations of the Mexican Cultural Heritage Gardens and Plaza.

The San José International Mariachi Festival and Conference takes place July 11­14. Workshops run Thursday­Saturday at San Jose State University; mariachis perform Friday­Saturday at the San Jose Center for the Performing Arts, $20­$60; the Mariachi Festival commences Sunday at 11am at Guadalupe River Park, free; 408/292-5197.